Tenter clip assembly



Jan. 21, 1964 J 5, PARKINSQN 3,118,212

TENTER CLIP ASSEMBLY Filed Feb. 1, 1962 2 Sheets-Sheet 1 l8 a ?FIG. I

U l8 --|e 2 O V o INVENTOR JOHN S. PARKINSON ATTORNEY Jan. 21, 1964 J. s. PARKINSON 3,118,212

TENTER CLIP ASSEMBLY Filed Feb. 1, 1962 2 Sheets-Sheet 2 FIG.2

| INVENTOR JOHN S. PARKINSON ATTORNEY United States This invention relates to an improved tenter clip assembly.

In order to tense or stretch webs of plastic films, fabrics, foils, etc., in the direction of their width, tenter frames are used. The tenter frame, as illustrated schematically in FIGURE 3, is composed of a pair of diverging tracks 23 and clips 1 arranged as part of two endless chain conveyors 3. Each track is composed of two rails, an inner guide rail 6 and an outer guide rail 7. The clips are adapted to grip the edges of the web 29. The chain conveyors are each adapted to be moved about two or more motor driven members (usually sprockets) 2 3 while being disposed in guiding contact with the rails of the diverging tracks during their forward movement. In this way, the clips on the chain conveyors serve to move th Web longitudinally while simultaneously stretching the web transversely.

The improvement that comprises the present invention i s in the web-gripping tenter clip assembl i.e. the combination of renter clip, chain and the means of attachment of clip to chain. Specifically, the clip assembly is made up of a substantially flat support member adapted for mounting on a. conventional chain conveyor, the support member having an integral Wear block with a thickened shoulder for slidably engaging the inner rail of one track of the two diverging tracks and also having an integral lug extending from the edge of the support member opposite the wear block for slidably engaging the outer rail of the track, means to connect the support member to the conveyor chain and a tenter clip composed of two jaws, preferably a movable upper jaw and a stationary lower jaw, said clip removably mounted on the support member and adapted to grip the edge of the web material between said jaws, said lower jaw resting on the horizontal upper face of the wear block.

To assist in understanding the invention, reference is made to the drawing, in which:

FIGURE 1 is an exploded view of the tenter clip illustrating the relationship of various elements to each other and to the chain;

FIGURE 2 is an end view, partly sectional of the entire assembly, including tracks; and

FEGURE 3 is the schematic illustration of a tenter frame.

T he major difficulties arising from tenter clip and chain assemblies previously known to the art are caused by excessive wear in the operative components of the assembly. The present invention avoids these difficulties by providing separate units to perform the separate functions of the assembly, resulting in longer wear for the entire assembly and enabling replacement of one unit without replacing the entire assembly.

FIGURE 1, an exploded View of the tenter clip assembly of the present invention, illustrates the relationship of the various elements. Wear casting or support member 2 composed of a fiat body section 17 with integral wear block and lug 3, in addition to other functions performed during operation, provides a source of attachment for the other members. The wear block 15 is in the form of a thickened, rectangular flange integral with and preferably at right angles to the flat body section 17. Wear block 15 has a smoothly machined fiat face 16 which in operation slides on one of the divergent rails "atent O "ice and takes the web-stretching load. A horizontal machined surface in a plane perpendicular to surface 16 is incorporated in the wear casting to take the downward component of the load. Extending from the side opposite wear block 15 is lug 8, also integral with body section 17. Lug 8 has a smoothly machined surface to engage a torquerestraining rail 7 of the track combination shown in FIG- URE 2. As further shown in FIGURE 1, the body section 17 of wear block 2 is drilled and tapped with holes 18 to threadably engage cap screws 5. Smooth openings 19 are provided to admit link pins 11. When assembled, link pins 11 extend up from chain 3 through openings 19. The pins 11 are held in place by lock plate 4. The chain, accordingly, is a standard chain, with special extended pins. The distance between openings 19 is selected to suit the chain pitch. All parts of the chain, being of steel, provide greater strength and better wearing properties than a chain composed of standard roller links coupled with a casting. Since the wear casting has no longitudinal tension function, a material especially suited for frictional wear can be used for construction. One such material is ductile cast iron.

A sectional view of the various elements of this invention and their functional relationships is provided by FIGURE 2. Referring to FIGURE 2, the machined portion of wear casting 2 abuts main rail 6 horizontally with a vertical wear surface against which the principal transverse load occurs; and vertically with a horizontal wear surface, to take the downward component. Side rail 7 is in sliding contact with integral lug 8 to restrain the upward component caused by tension of the Web. Main rail 6 and side rail 7 are held in position on framework 23 of the track by a plurality of cap screws 9A, 9B and it). The contacting parts of rail 6 and rail 7 are usually of cast iron or cast steel but may be of any suitable material including plastics.

The tenter clip-wear casting sub-assembly 2 is attached to chain 3 by pins 11. Pins 11 extend through chain 3, which is usually a standard roller-link chain. As stated previously, pins 11 of the links to which the clips are attached are longer than the standard pins. These extended pins 11 are provided with a circumferential channel 22 near the end to provide access for elongated notch 13 of the lock plate 4. Notches 13 of lock plate 5 are of such width as to just admit channel 22 of pins 11. When assembled as shown in FlGURE 2 between the clip subassembly El and wear block sub-assembly or support member 2, lock plate 4 is retained in position by cap screws 5 which pass through openings 14 and threadably engage support member 2. Lock plate 4 is fabricated from hardened sprin steel, of about 16 gauge. Clip sub-assembly 1 is provided with counterbore 21 to admit the ends of pins 11. The particular design of the web-gripping device 12 is not critical but a matter of choice. As shown, it is pivoted or hinged about the pin 25 which, in turn, is disposed in an appropriate opening in the arm as of the clip 1. The clips are positioned along the chain accord ing to the usual practice.

It is found that the tenter clip and chain assembly of this invention operates quite satisfactorily with lower power and with considerably less oil than is required for conventional assemblies. Further, for some applications, the side rails 7 can be fabricated from non-metallic materials employing self-contained lubricants.

The plane-faced wear block which slides on a flat rail, as described above, has been found workable, easily replaceable and easy to construct. Any wear that occurs, occurs principally at the top edge as a result of the moment of force applied by the web. Accordingly, a wear casting wherein the wear block has a cylindrical face which rides in a concave track with a semi-circular crosssection may wear more uniformly. The cylindrical wear block permits a slightly greater tendency to rotate, but the leverage afiforded by the lug (corresponding to lug S of FEGURE 2) would permit operation with barely appreciable increased'wear on the lug or the inner rail. The cylindrical wear block in combination with the concave track is intended to be within the scope of the present invention.

Having fully disclosed the invention, what is claimed is:

1. In a tenter frame for stretching Web material transversely comprising a pair of diverging tracks, each track composed of an inner rail and an outer rail; two endless chain conveyors, each adapted for movement in said diverging tracks; and a plurality of tenter clip assemblies disposed on each chain conveyor adapted to grip the edges of a web to be stretched, the improvement wherein said tenter clip assembly comprises a substantially fiat support member separate from and adapted for attachment to said chain conveyor, the support member having an integral wear block with a thickened shoulder for slidably engaging the inner rail of one track of said two diverging tracks and also having an integral lug extending from the edge of the support member opposite the wear block for slidably engaging the outer rail of said track; means t connect the support ember to the conveyor chain and a ten er clip removably mounted on the support member and adapted to grip the edge of the web material.

2. In a tenter frame for stretching web material transversely comprising a pair of diverging tracks, each track composed of an inner rail and an outer rail; two endless chain conveyors, each adapted for movement in said diverging tracks; and a plurality of tenterclip assemblies disposed on each chain conveyor adapted to grip the edges of a web -to be stretched, the improvement wherein said tenter clip assembly comprises a substantially fiat support member separate from said adapted for attachment to said chain conveyor, the support member having an integral-wear block with a thickened shoulder for slidably engaging the inner rail of one track of said two diverging tracks and also having an integral lug extending from the edge of the support member opposite the wear block for slidably engaging the outer-rail'of said track; means to connect the support member to the conveyor chain, said connecting means being separate from said conveyor; and a tenter clip removably mounted on the support member and adapted to grip the edge of the web material.

3. In tenter frame for stretching Web material transversely comprising a pair of diverging tracks, each track composed of an inner rail and an outer rail; two'endless chain conveyors composed of linlis, each conveyor adapted for movem nt in said diverg ng tracks, and a plurality of tenter clip assemblies disposed on each chain conveyor ad'a ed to grip'the edges of a web to be stretched, the improvement wherein said tenter clip assembly comprises a substantially fiat support member separate from and adapted for attachment to'said chain conveyor, the sup port member havin an integral wear block with a thickened shoulder for sildably engaging the inner rail of one track of said two diverging tracks and also having an integral lug extending from the edge of the support member opposite the wear block for slidably engaging the outer rail or" said track; a plurality or" openings in said support member; a plurality of elongated pins adapted to pass through the links of said conveyor chain and through said openings in said support member, each of said pins having a circumferential groove in proximity to one extremi j of each of said pins; a slotted plate adapted for mounting on said support member and to engage the circumferential groove of each of said pins whereby the support member is connected to said conveyor chain; and a center clip removably mounted on said plate and said support member adapted to grip the edge of the Web material.

References fiiedin the file of this patent UNITED STATES PATZNTS 2,235,820 MacKnight June 9, 1942 2,472,375 Hirinekens June 7, 1949 2,736,082 Dungler Feb. 28, 1956 3,058,191 Nash Oct. 16, 1962 UNITED STATES PATENT OFFICE QERTIFICATE 0F 0 EC'HN Patent Non 3 l18 212 January 21 1964 John S, Parkinson It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected belowa Column 3 line 37 for "said" read and Signed and sealed this 16th day of June 1964,

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. IN A TENTER FRAME FOR STRETCHING WEB MATERIAL TRANSVERSELY COMPRISING A PAIR OF DIVERGING TRACKS, EACH TRACK COMPOSED OF AN INNER RAIL AND AN OUTER RAIL; TWO ENDLESS CHAIN CONVEYORS, EACH ADAPTED FOR MOVEMENT IN SAID DIVERGING TRACKS; AND A PLURALITY OF TENTER CLIP ASSEMBLIES DISPOSED ON EACH CHAIN CONVEYOR ADAPTED TO GRIP THE EDGES OF A WEB TO BE STRETCHED, THE IMPROVEMENT WHEREIN SAID TENTER CLIP ASSEMBLY COMPRISES A SUBSTANTIALLY FLAT SUPPORT MEMBER SEPARATE FROM AND ADAPTED FOR ATTACHMENT TO SAID CHAIN CONVEYOR, THE SUPPORT MEMBER HAVING AN INTEGRAL WEAR BLOCK WITH A THICKENED SHOULDER FOR SLIDABLY ENGAGING THE INNER RAIL OF ONE TRACK OF SAID TWO DIVERGING TRACKS AND ALSO HAVING AN INTEGRAL LUG EXTENDING FROM THE EDGE 